Summit has issued a statement as far as Casting Directors for Breaking Dawn...
According to a new releases, Debra Zane, who handled casting for the first three movies, and is based in LA is over seeing two other firms that will handle casting duties for locations in Baton Rouge, La and Vancouver.
These are the only three casting firms that will cast characters or extras when need be and Summit wants fans to remember not to get caught up in phony casting calls for the film.
Check out the list here: http://vatwilightmoms.blogspot.com/2010/08/breaking-dawn-official-casting.html?spref=tw
Source: Virginia Twilight Moms